The invention concerns a bolting device, especially for coke-oven doors.
Bolting, in particular of coke-oven doors, is accomplished mostly by means of L-shaped throw bolts which are mounted on the door panel in a manner allowing them to pivot, and which, when in locked position, will engage, from behind and with their free ends, a usually hook-shaped strike.
The sealing strips, frequently clamped to the door panel and normally adjustable, are usually constructed as metallic straight edges (so-called "hammer-tap edges"), but they can, of course, also be of a different construction. The advantage of metallic sealing edges, which allow later straightening by hammer tapping, lies however in the fact that they more readily allow compensating for thermal distortions, and by this ensure better sealing.
If done by mechanical means alone, locking of the door panel against the door frame, as described afore, has the disadvantage of requiring exceedingly great forces, for locking as well as for unlocking, in order to generate the high contact pressure required. To prevent the locking device from becoming loose under the varying thermal influences during operation, very small wedge angles have to be provided at the strike hooks, and these angles, in turn, will cause exceedingly high friction forces during locking as well as unlocking and thus make it difficult to perform satisfactory locking and unlocking with reasonable expenditure of force.
Numerous proposals to ameliorate this deficiency are known, most of which in the direction of so designing the pivot bearing, that serves to support the lock bolts and allows their rotation, that it can be movable in an axial direction. Attaching the pivot so that it can adjust itself in an axial direction will enable moving the bolt into locked position with a relatively small expenditure of force, and to perform the actual pressing-on only subsequently by appropriate axial adjustment of the pivot bearing serving as support, and allowing the rotation, of the lock bolts. The procedure on unlocking is such that initially the state of tension between lock bolts and strikes is relieved by adjustment of the pivot bearing, and only thereupon the lock bolt is turned to the unlocked position.
A known design according to this general principle of solution consists of interposing a spring cylinder between the axially adjustable pivot bearing and the bottom of the door panel, whereby suitable pre-compressed Belleville springs will generate the actual contact pressure, and to so design the pivot bearing for the throw bolt that it can be axially adjusted by an externally actuated threaded spindle, and that by actuation of the spindle, the pivot bearing will compress the Belleville springs beyond their pre-tensioning required for operation, and thus facilitate the locking and unlocking procedure every time before it is initiated. Relieving of the state of tension between the ends of the bolts and the strikes will allow throwing of the bolt, from this position to the unlocked position, with relatively small forces. Locking is accomplished in an analogous manner by first compressing the pre-loaded assembly of Belleville springs through actuation of the threaded spindle, and only thereupon throwing the bolt into the locked position, before the subsequent actuating of the spindle to relieve the spring back to the pre-loading required for operation and to concomitantly produce the required tension between lock bolts and strikes.
This known solution has led to considerable difficulties in practice, and is thus unsatisfactory in its results.
Disregarding the fact that this design is relatively complicated and thus costly to produce, it has proved to be difficult, on one hand to anchor the threaded spindle at the bottom of the spring cylinder so that it will not be torn out, and on the other hand to actuate it, for instance through an electric rotary drive, rapidly and exactly, as would be desirable in the interests of keeping time losses down to the possible minimum.
These disadvantages are, however, avoided by another known bolting device, (German Letters Patent No. 916 885), in which the axial adjustment of the pivot bearing which serves as the pivotal support of the bolt, is accomplished by a piston-operated adjusting cylinder with preferably hydraulic actuation.
On the other side, this principle of solution has the deficiency that the contact pressure required for operation, must be generated by the pressure medium within the adjusting cylinder. In practice, it might be difficult, if not quite impossible, to maintain the pressure medium contained within the adjusting cylinder at the required steady operating pressure over the entire locking period, considering that during the coking period, the cylinder and the pressure medium contained therein, are subjected to varying temperature influences.
Added to this is the disadvantage that in this case the adjusting cylinder must be of a type allowing pressure action on both sides, and alternating venting of both cylinder sides when actuating the adjusting device of the pivot bearing, which is time-consuming and also requires pressure media of different pressure levels.
Finally, a bolting device is known, (German Letters Patent No. 870 992), where the pressure action upon the spring, for the locking or unlocking procedure, is accomplished by a liquid or gaseous medium within a circular hose made of an elastic material, whereby the hose which is resting on one side against the cover of the housing, can be filled with the pressure medium, thereby forcing a pressure plate, that is linked to the shaft of the bolt, against the spring arranged at the other side of the pressure plate. At its outer rim, the pressure plate shows a gap against the housing containing it, and one or two pins are arranged at the rim to serve as stops to prevent complete compression of the hose by the spring. The pressure plate is supported at one end in a recess in the center of the housing cover, and at the other at the door end of the housing, through a journal at the shaft of the throw bolt, the shaft being connected to the pressure plate. The shaft has a thread which engages the pressure plate. Turning the throw bolt which is in fixed attachment to it, the entire shaft will thus also revolve.
On one side, this device has the disadvantage of consisting of quite many individual parts difficult to manufacture, and also of using an elastic pressure hose which is extremely failure-prone under the severe working conditions prevailing at a coke oven. On the other side, it is of disadvantage that a not inconsiderable quantity of the pressure medium is continually present between the pressure plate and the housing cover, so that in the event of possible leaks, quite a large quantity of the usually liquid pressure medium can escape, or, air can enter unnoticed and lodge as bubbles within the pressure hose. Just this last-named failure can be particularly troubling in hydraulic systems, as, under variable temperature conditions, especially under the usual temperature rise ensuing at the coke-oven door during the coking period, considerable pressure may be generated within the pressure hose, which will lead to further precompressing of the spring at the other side of the pressure plate and thus relieve the bolt, which will impair the sealing of the coke-oven door. This effect, however, will also already occur if the space wherein the pressure medium is contained is well vented, since every expansion of the volume of the pressure medium will fully affect the pressure plate.